OCR Text |
Show How "Assayini;" Is Done. The process of assaying gold and silver is identical in each case. The metal is first put through a highly heated furnace and melted, tho samples for "assay" being dipped out while the metal is in a liquid state. Next, the sample is thrown into a vessel of cold water, when granulation granu-lation ensues.' Taken from the cold bath, it is boiled in sulphuric acid, the silver dissolving while the gold is precipitated pre-cipitated to the bottom, where it is caught in proper receptacles. The acid is now drawn off and the metal placed in another vessel laid with sheet lead, the bottom being plates of copper. Chemical action now sets in, the acid, copper and lead being in a ferment. While the gold is being precipitated, the silver, if there be any in the sample under test, is being deposited in thin metallic sheets on what before the fer- mentation set in were the copper plates, but which have now been transformed into blue vitriol or sulphate of copper. After the metals have all been deposited they are gathered up, and, with the impurities im-purities still remaining, pressed into cakes by a hydraulic machine which has a pressure of 200 tons. Again it is melted (the gold and silver each in separate sepa-rate vata, of course), the pure metal being be-ing again deposited and the impurities, aided by chemical action, left floating on the top. The next and last process runs the metals into ingots ready for tho markets of the world. St. Louis Repub-' Repub-' lie, |